Recently, multifunction peripherals (MFPs) having a plurality of functions have been used in offices and so on. Multifunction peripherals are often used in situations where they are connected via a network, such as a LAN (local area network), to information processing terminals, such as personal computers.
In such multifunction peripherals, a function of, when not in use, switching their power supply mode from a mode for supplying power to the whole of the multifunction peripheral to a low-power consumption mode (sleep mode) in which the power consumption is reduced is widely adopted. This function enables reduction of environmental load. Furthermore, apparatuses employing an off mode are recently emerging. The off mode refers to a mode in which a plug is connected to an outlet but power is substantially in the off state, for example, a mode in which only the operation of a power key (power button) provided on an operating panel or the like can be detected and power supply to other components of the multifunction peripheral is stopped. The adoption of this off mode enables the multifunction peripheral to meet the demand for further reduction of power consumption, such as the European ErP (Energy-related Products) Directive.
The transition to the off mode can be achieved, for example, by operating the above-mentioned power key. Recently, multifunction peripherals have been provided with multiple operating keys including a power key and have widely employed a configuration in which a CPU detects key operations of the multiple operating keys (see for example Patent Literature 1). This configuration enables key operations to be efficiently detected.
However, in the configuration in which the CPU detects key operations, once an abnormal state (disabled state), such as runaway, occurs in the CPU, the CPU becomes no longer able to detect any key operation. In this case, the CPU also becomes unable to detect any operation of the power key. Therefore, it is also impossible to achieve the transition of the power supply mode to the off mode by operating the power key and thus shut off power supply to the CPU. In this situation, it may be possible to pull the plug out of the outlet to forcedly shut off power supply. However, the outlet is often located at a place where the user readily cannot insert and remove the plug, such as a wall surface behind the multifunction peripheral. Furthermore, such a power shut-off manner may damage to an HDD and other devices mounted in the multifunction peripheral.